In recent years, a light emitting device using a light emitting element represented by an electroluminescence (EL) element and the like has been researched and developed as a substitute for a liquid crystal display (LCD) having pixels which employ liquid crystal elements. The light emitting device has advantages of high image quality, wide viewing angle, and thin shape with lightweight due to needlessness of a backlight since the light emitting device is of the self-emission type, etc. By making use of these advantages, the light emitting device is expected to be widely used for display screens of cellular phones or display devices.
In addition, a portable information terminal that provide high added value has been required as a result of diversification of the intended use. Recently, a portable information terminal having a sub screen formed on the backside of a normal main screen has been provided (for instance, see following Patent Document 1 and Patent Document 2).
[Patent Document 1]
Japanese published unexamined No. 2001-285445
[Patent Document 2]
Japanese published unexamined No. 2001-86205